Bagging machine with integrated printer

ABSTRACT

A method for printing indicia on bags interconnected in a continuous web. A bagging machine has a printer and a plurality of tensioning rollers, at least one of which is driven by a roller motor. The web is moved from an initial bagging machine station through a print station and to a load station in which goods are placed in the bags. A perforation sensor featuring a spring biased hemispherical tip indicates to a bagging machine controller that a perforation is present. First roller motor control signals are received from a printer controller comprising a frequency modulated first motor speed signal and a first motor enable signal. The first roller motor control signals are transmitted to the roller motor to cause it to drive the roller to move bags through the print station. Second roller motor control signals are received from the bagging machine controller comprising a frequency modulated second motor speed signal and a second motor enable signal and these signals are transmitted to the roller motor to cause the motor to drive the roller to move bags to the final station. This cycle is repeated such that at any given time either first roller motor speed signal or the second roller motor speed signal, but not both simultaneously, are being transmitted to the roller motor. This is accomplished by providing a control signal to a multiplexer that provides a selected speed signal to the roller motor based on the control signal. The speed signals are generated by selecting resistor components that are coupled to a voltage controlled oscillator to provide a frequency modulated motor speed signal. A perforation sensor featuring a spring biased hemispherical tip indicates to the bagging machine controller that a perforation is present.

FIELD OF THE INVENTION

[0001] The present invention concerning a bagging machine having anintegrated printer for printing indicia onto a bag just prior to loadingthe bag with one or more articles. The invention is particularly wellsuited for packaging quantities of pharmaceuticals to fill individualorders and the process of filling such orders as well as other mailorder applications.

BACKGROUND ART

[0002] Machines that use webs of preopened bags to form packages are nowwell known. Such webs of bags are disclosed and claimed in the U.S. Pat.No. 3,254,828 entitled Flexible Container Strips (the Autobag Patent). Amachine that is currently in wide usage commercially for formingpackages from chains of preopened bags is described in U.S. Pat. No.5,394,676 (the Excel Patent). Machines made in accordance with theteaching of the Excel Patent often are supplied parts to be packaged bymodular systems of counters and/or weighers and conveyors in order thatpackages can be formed automatically and at relatively high speeds.

[0003] The Excel machines are often equipped with printers such as thatdescribed and claimed in U.S. Pat. No. 5,371,521 issued Dec. 6, 1994 toRick S. Wehrmann (the Teeter Totter Patent). The Teeter Totter Patent isdirected to a mechanism which tensions the film and feeds it past aprint head in a section of a web of bags that is isolated from a sectionwhich feeds bags to a load station such that the two sections areindependently tensioned. The Excel Patent teaches a dancer mechanismwhich independently tensions a web section upstream from the printersection so that there are three isolated individually tensioned sectionsalong the feed path of an Excel machine equipped with a printer. Whilethis system is efficient for printing multiple bags with the sameinformation, the presence of a number of bags between the printer andbagging machine complicates the process of changing over the printedindicia and may result in a number of scrap bags if the bagging machinejams.

[0004] Relatively large “mail order” organizations with systems forfilling pharmaceutical orders for home delivery require differentprinted information on each bag. To package their orders, these mailorder organizations typically utilize so-called wicketed bags forpackaging individual orders for shipment. Pressure sensitive labels areused to identify the contents of the given bag and to provide an addressfor shipment of the bag to the customer. The wicketed bag approach isslow and expensive. It is especially expensive in that only registeredpharmacists can fill individual bags with pharmaceutical orders.

[0005] A machine that is a modified version of the Excel machine iscurrently being offered for sale. This modified machine has whatfeatures a “ditch” to receive and accumulate bags after they have beenprinted but before they are fed to a load station. This accumulation ofbags results in printing errors and wrinkling of bags resulting infinished packages that are not as attractive as they should be. Suchwrinkling can make bar codes printed on the bags unreadable.

[0006] Accordingly it would be desirable to provide a machine which usesa web of preopened bags for packaging individual orders and which printsidentifying information on a bag immediately before it is loaded andsealed.

SUMMARY OF THE INVENTION

[0007] A bagging machine having a drive roller for engaging a surface-ofan endmost bag in a chain of interconnected bags and moving the endmostbag to a bagging station. A supply of interconnected bags supplies bagsto the bagging station. A motor rotates the drive roller in a controlledfashion to route the interconnected bags along a travel path to thebagging station from the supply. A printer positioned with respect tothe endmost bag can apply indicia unique to the endmost bag prior tofilling the endmost bag with one or more articles at the baggingstation. A controller applies energization signals to the motor forcontrolling movement of the endmost bag. The controller has an interfacewith both the motor and the printer to coordinate movement of theendmost bag with printing of indicia by the printer. By switchingcontrol of the motor between the printer and bagging machine, it ispossible to print a bag just prior to its being filled therebystreamlining the bagging process.

[0008] According to an embodiment of the present invention, indicia isprinted on bags interconnected in a continuous web and being processedby a bagging machine having a printer and a plurality of tensioningrollers that move the web from an initial bagging machine stationthrough a print station and to a final station, such as a load station.At least one of the rollers is driven by a roller motor that iscontrolled according to the present invention. A perforation sensorfeaturing a spring biased hemispherical tip indicates to a baggingmachine controller that a perforation is present. First roller motorcontrol signals are received from a printer controller and transmittedto the roller motor to cause the motor to drive the roller to move bagsthrough the print station. Second roller motor control signals arereceived from the bagging machine controller and transmitted to theroller motor to cause the motor to drive the roller to move bags to thefinal station. These steps are repeated such that at any given timeeither first roller motor control signals or second roller controlsignals, but not both simultaneously, are being transmitted to theroller motor. In an exemplary embodiment, the bagging machine controllertransmits third motor control signals to the roller motor after the bagsreach the final station to cause the roller to move bags in a reversedirection away from the final station a predetermined distance toreposition a given bag for printing.

[0009] According to a feature of the present invention, the motorcontrol signals include motor speed, acceleration, enable signals. Themotor speed signals received from the printer may correspond to a slowerroller speed to accommodate printer speed while the motor speed signalsform the bagging machine may correspond to higher speeds to speed upoverall operation. According to a feature, the first and second rollermotor control signals are frequency modulated signals wherein thefrequency of the signal corresponds to a desired motor speed.

[0010] The synchronization of signals from the bagging machine andprinter is accomplished by forming a logical OR combination of motorenable signals from the printer controller and the bagging machinecontroller and by providing a control signal to a multiplexer thatprovides a selected speed signal to the roller motor based on thecontrol signal. According to a feature the motor speed signal isprovided by selecting resistor components that are coupled to a voltagecontrolled oscillator to provide a frequency modulated motor speedsignal.

[0011] These and other objects, advantages, and features of theinvention will be better understood from the accompanying detaileddescription of a preferred embodiment of the invention when reviewed inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a perspective view of a bagging machine constructed inaccordance with an exemplary embodiment of the invention;

[0013] FIGS. 2A-2C are block diagrams illustrating control components ofthe bagging machine of FIG. 1;

[0014]FIG. 3 is a side elevation view of a printer and feed rolls thatmove a bag into a loading station;

[0015]FIG. 4 is an enlarged elevation view of the depiction of FIG. 3showing a print head and perforation detecting device;

[0016] FIGS. 5A-5C are electrical schematics of a portion of a baggingmachine controller for coordinating movement of a chain of bags withprinting by the printer on those bags;

[0017]FIG. 6 is an exploded view of the perforation detecting deviceshown in FIG. 4; and

[0018]FIG. 7 is a flow diagram of a method employed by the baggingmachine of FIG. 1.

EXEMPLARY EMBODIMENT OF THE PRESENT INVENTION

[0019]FIG. 1 illustrates a bagging machine 10 that includes a userinterface 12 that allows a user or operator to adjust various baggingparameters such as seal temperature, bag length, time between cycles foran automated loading system and the like. The user interface issupported by pedestal support 14 which in turn is supported by a base 16having generally horizontal support members 16 a, 16 b, 16 c thatinclude rollers for repositioning the bagging machine 10.

[0020] The bagging machine defines a bagging station indicated generallyas 20 which is a position where articles can be dropped into the endmost bag of a chain of interconnected bags. Just prior to the baggingstation the machine 10 includes a pair of feed rollers 22, 24 (FIGS. 3and 4) for driving an end most bag (not shown) of the chain ofinterconnected bags from a supply (not shown). The supply contains acoiled sequence of interconnected plastic bags separated from each otherby perforation lines that extend across the width of the bags and alloweasy separation of the bags once an endmost bag has been filled. Thesupply is mounted for rotation to a spindle 32 to dispense the outermostlayer of bags from the supply.

[0021] During machine set up, an operator unwinds the chain of bags fromthe supply and routes the bags through a dancer roll assembly 34underneath a printer 40 and into a nip 42 formed by the two driverollers 22, 24 (FIGS. 3 and 4). The dancer roll assembly 34 similar tothe dancer roll assembly shown in U.S. Pat. No. 5,341,625. A separatedrive roll pulls the chain of bags from the supply during operation ofthe bagging machine and the dancer roll assembly 34 maintains a tensionbetween the supply and the dancer assembly while allowing the nip of thedrive rollers 22, 24 to intermittently pull bags through a region ofprinting to the bagging station. An orientation of the dancer rollassembly controls intermittent operation of this separate drive roll.After passing through the dancer assembly 34, the bags move upward awayfrom the dancer roll along a bag path of travel past the printer 40where indicia is applied to each bag under the control of an electroniccircuit to be described in greater detail below.

[0022] At the bagging station, the bag is held open by a stream of air(not shown) so that the articles can be either manually dropped througha chute into a bag or brought to the bagging station by a conveyor (notshown) which drops the articles into a chute and into an opened end mostbag that is still attached to the serial chain of interconnected bags.The filled bag is then sealed and separated from the chain for removalfrom the bagging station to a separate location.

[0023] One feature of the invention is an ability to print informationonto the bag immediately before the bag is moved forward to the baggingstation where articles are inserted into the bag. One application towhich the bagging machine built in accordance with the invention hasspecial utility is for bagging prescription drugs. Information specificto the end user such as an address and instructions for taking the drugsas well as the contents of the bag are printed on the bag immediatelybefore the prescription drug is loaded into the bag. Practice of thepresent invention allows information to be printed onto the bag justprior to movement of the bag to a position for loading.

[0024]FIGS. 3 and 4 are side elevation views of the printer 40 that islocated in close proximity to the bagging station to facilitate printingon bags immediately prior to their being filled. As is shown in FIG. 3,the printer includes a reel-to-reel type system for delivering printribbon to a print station above the bag in a controlled manner. A supplyroll 50 rotates in a clockwise direction to feed a printer tape (notshown) over a pulley 54 to the print station 56 where indicia is appliedto a generally flat outer surface of the bag that is about to be filled.The spent print tape is reeved around a second pulley 60 at the locationof the print station 56 and returned to a pick up roll 62, whichrotates, in a counterclockwise direction and is located to the right ofthe supply roll 50 in FIG. 2.

[0025] A print head 70 is shown in greater detail in FIG. 3. The printhead 70 includes a heating element. The heating element selectivelyapplies heat to the tape and through a known thermal transfer processapplies the indicia to the bag from the printing tape. Selectiveenergization and thus heating of the print head element is controlled bya controller within the printer 40. The print head controller encodesthe bag with information supplied to the printer from a separate datasource. In the disclosed embodiment of the invention, the separate datasource is a database stored on a separate computer, which is downloadedto the printer 40 by means of a serial communications port coupledbetween the separate computer and the printer 40. This seriallytransmitted information is received by a controller within the printer,which then selectively energizes the thermal print head in a manner toencode the information onto a bag.

[0026]FIG. 3 also illustrates the feed rollers 22, 24 that defines a nipfor moving the end most bag from the region of the printer and printhead to the bagging station. As seen in the enlarged view of FIG. 4,there are two rollers, which define a nip 42 through which the bag isrouted during setup. The bottom most roller 22 is a driver roll so thatcontroller rotation of this roller moves the bag through the nip to thebagging station. The roller 22 is coupled by means of a transmission toa stepper motor (shown schematically as 140 in FIG. 2A) having an outputshaft whose speed of rotation is controlled by a bagging machinecontroller (shown schematically as 130 in FIG. 2A). The top most roller24 is spring loaded against the driver roller 22 by a spring 19 and isdriven by the frictional engagement therebetween.

[0027] It is a feature of the invention that this driver roller 22 canbe reverse activated to retract the bag through the nip after thepreceding bag has been loaded, sealed and separated thereby allowingprinting to occur over most of the bag's surface. This backwardsmovement of the bag is accomplished in part by use of a new perforationsensor 100 (shown in detail in FIG. 6) for sensing bag location. A printroll 80 in immediate proximity to the print head is driven by a belt 81connected to the driver roll 22 and supports the bag in the region theprint head applies indicia to the bag. During reverse actuation of thedriver roll 22, as will be discussed in greater detail later, the dancerroll assembly pulls the chain of bags backward by the weight of thedancer roll to maintain a tension in a region of the printer.

[0028]FIG. 6 is an exploded perspective view of a perforation sensor 100which is shown in phantom in the side view of FIG. 3. The sensor 100includes a metal semi-hemispherical tip 102 which engages the bag as itmoves past the sensor 100. This tip is biased against the bag by acompressed spring 104 trapped within a cylindrical sleeve 110, which inturn is mounted to a flange 112 electrically coupled to high voltagesource of power. The energization from the source occurs through a tab,which is spaced from the cylindrical sleeve 110. When supported withinthe sleeve, the tip 102 contacts the bag and as the bag moves, atperiodic intervals, a transverse line of perforations passes over thesensor 100. When this occurs, there is a region of low dielectricconstant i.e. the air between the sensor and a metal backing (not shown)against which the sensor is biased. This low dielectric results in aspark occurring, which is fed back through the high voltage input to thesensor to a sensing circuit. This causes a reduction in the voltage dueto the periodic shorting of the perforation sensor 100, which in turnindicates to the drive control that the bag has reached a certainlocation with respect to the print head and the bagging station. Duringintervals in which the bag (without perforations) is between the sensorthe metallic backing, the die-electric constant is higher and inhibitsthe sparking that occurs when the perforations are sensed.

[0029] Bagging Machine Controller

[0030]FIGS. 2A through 2C are block diagrams of the control system 130for the bagging machine. The stepper motor 140 that drives the driverroll 22 (FIG. 3) is controlled by signals provided to a control adapterboard 133 b by a sequencer 131. The sequencer switches control of thestepper motor 140 between controls associated with the bagging machine132 and controls associated with the printer 133. In doing so, thesequencer 131 causes the motor to be controlled by the device utilizingthe motor at any given time. For example, during the printing intervalof the cycle, the printer controls 133 cause the motor to rotate thedriver roll 22 at a relatively slow speed. The printer controls 133 mayalso rotate the drive roll at an intermediate indexing speed toprecisely position the bag for the next printing interval. Afterprinting, the bagging machine controls cause the motor to rotate thedriver roll at a relatively high speed to place the bag in loadingposition and to move the bag backward to tear the bag away from the weband, if necessary, move the web further back to position the next bag inits print position.

[0031] The sequencer 131 contains a microcontroller (U1 in FIG. 5A)designated PIC16C74B −20/P (supplied by Microchip located in Arizona).An assembly language program is resident in memory on themicrocontroller for controlling the stepper motor 140 based on signalsfrom a bagger controller 132 and a printer controller 133 a. The steppermotor 140 receives an enable signal, S_MENA, and a frequency modulatedsignal, S_MSTEP, that controls the speed and rate of acceleration of thestepper motor from a motor control board 133 b that is resident on theprinter controller. S_MENA is provided by an OR combination performed bya sequencer enable module 138. The motor enable signal from the baggingmachine (STEP_INH) is combined with a motor enable signal from theprinter (MENA) such that if either device is providing an enable signal,the motor 140 is enabled. S_MSTEP is derived from the sequencer and morespecifically by a selection of resistor components coupled to a voltagecontrolled oscillator U5 shown in FIG. 5B whose output is ESTEP_CLK. Thesequencer 131 controls a multiplexer 138 that provides the signalS_MSTEP by switching between a signal provided by the bagging machine(ESTEP_CLK) and a signal provided by the printer (MSTEP).

[0032] Referring to FIGS. 2A-2C and also to FIG. 7 wherein a flowdiagram of a bagging method 150 employed by the sequencer to control theoperation of the bagging machine is depicted. The sequencer 131 is cuedto begin a print portion of a bagging machine cycle by a start of cycle,SOC, signal from the bagger controller 132 in step 155. The sequencersignals the printer to start printing by setting an appropriate bit onthe /FULL line in step 160. In step 165 the printer controller 133 thenpasses MSTEP and MENA, step motor and motor enable signals,respectively, back to the sequencer 131. The MSTEP signal is input tothe multiplexer 138 that is used to generate the S_MSTEP signal sent tothe motor control board 133 b to control the speed and rate ofacceleration of the stepper motor 140 in step 170. When the printer hasfinished printing, it sets the MENA bit to “inactive” to indicate thatit is finished in step 175. The sequencer 130 then passes the ESTEP_CLKsignal from the bagger controller 132 to the multiplexer 138 in step 180to generate the S_MSTEP signal sent to the motor control board 133 b instep 185. The bagger controller 132 signals it has positioned theprinted bag in load position by setting the STEP_INH bit to “inactive”in step 190. After step 190, the sequencer waits for the SOC from thebagger and meanwhile the bagger controller causes the stepper motor 140to reverse the web of bags to tear the printed bag off and position thenext bag for printing. The sequencer continues cycling stepper motorcontrol between the printer and bagger controllers in this manner.

[0033] FIGS. 5A-5C are a detailed schematic of the circuitry, which ismounted to a board contained within the existing Excel bagger system.This circuit board implements functionality previously implemented on aprinter circuit board so that there has been a modification to thecontrol to the printer to accommodate different operation by theexisting bagger. FIG. 5A depicts a programmable controller U1 thatcontains a memory having less than 256 bytes of control program forimplementing the control function of the printer and a secondprogrammable logic array U4, that interfaces with the microprocessorthat controls printing. Several relevant signals referred to in FIGS. 2and 7 are labeled in FIG. 5A for convenience. The source code (writtenin assembly language) for the programmable controller shown in FIG. 5Asits in an idle loop waiting for receipt of the start of cycle signal.Receipt of this signal causes the controller to perform one of itscontrol functions depending upon the status of various bytes that areset and as outlined in the flow diagram of FIG. 7.

[0034]FIG. 5B illustrates schematically a phased lock loop circuit andspecifically the phase lock loop circuit includes a voltage controloscillator U3 that is used during ramp up of the motor ramp down of themotor as the bag is driven from its position under the printer head tothe bagging station. This occurs in a controlled fashion by means of theprogrammable controller U1 that outputs a signal correlating to thedesired speed for the motor as ESTEP_CLK. U3 also feeds the ESTEP_CLKsignal back to logic array U4. FIG. 5C is an interface diagram thatincludes an input, MENA, from the precision printer central processingunit 133 a indicating a motor enable signal, S_MENA, is appropriatesince the print function has been completed.

[0035] While a detailed description of an exemplary embodiment of thepresent invention has been described with a degree of particularity, itis the intent that the invention include all modifications andalterations from the disclosed design falling within the spirit or scopeof the appended claims.

we claim 1) A method for printing indicia on bags interconnected in acontinuous web and being processed by a bagging machine having a printerand a plurality of tensioning rollers that move the web from an initialbagging machine station through a print station and to a final station,wherein at least one of the rollers is driven by a roller motor, themethod comprising the steps of: a) receiving first roller motor controlsignals from a printer controller; b) transmitting the first rollermotor control signals to the roller motor to cause the motor to drivethe roller to move bags through the print station; c) receiving secondroller motor control signals from a bagging machine controller; d)transmitting the second roller motor control signals to the roller motorto cause the motor to drive the roller to move bags to the finalstation; and e) repeating steps a-d such that at any given time eitherfirst roller motor control signals or second roller control signals, butnot both simultaneously, are being transmitted to the roller motor. 2.The method of claim 1 wherein the final station is a load stationwherein bags are filled with goods.
 3. The method of claim 1 wherein thebagging machine controller transmits third motor control signals to theroller motor after the bags reach the final station to cause the rollerto move bags in a reverse direction away from the final station apredetermined distance to reposition a given bag for printing.
 4. Themethod of claim 1 wherein the first roller motor control signalscomprise a motor enable signal.
 5. The method of claim 1 wherein thefirst roller motor control signals comprise a motor speed signal.
 6. Themethod of claim 1 wherein the second roller motor control signalscomprise a motor enable signal.
 7. The method of claim 1 wherein thesecond roller motor control signals comprise a motor speed signal. 8.The method of claim 1 wherein the first roller motor control signalscomprise a motor speed signal and the second roller motor controlsignals comprise a motor speed signal and wherein the first motor speedsignal corresponds to a slower roller speed than the second motor speedsignal.
 9. The method of claim 1 wherein the first and second rollermotor control signals comprise frequency modulated signals wherein thefrequency of the signal corresponds to a desired motor speed.
 10. Themethod of claim 1 wherein the first roller motor control signalcomprises a signal that corresponds to a rate of acceleration for themotor.
 11. The method of claim 1 wherein the second roller motor controlsignal comprises a signal that corresponds to a rate of acceleration forthe motor.
 12. The method of claim 1 wherein step e is performed byforming a logical OR combination of motor enable signals from theprinter controller and the bagging machine controller.
 13. The method ofclaim 1 wherein step e is performed by providing a control signal to amultiplexer that provides a selected speed signal to the roller motorbased on the control signal.
 14. The method of claim 1 wherein one ofthe roller motor control signals comprises a motor speed signal and themotor speed signal is provided by selecting resistor components that arecoupled to a voltage controlled oscillator to provide a frequencymodulated motor speed signal.
 15. A method for printing indicia on bagsinterconnected in a continuous web and being processed by a baggingmachine having a printer and a plurality of tensioning rollers that movethe web from an initial bagging machine station through a print stationand to a load station in which goods are placed in the bags, wherein atleast one of the rollers is driven by a roller motor, the methodcomprising the steps of: a) receiving first roller motor control signalsfrom a printer controller comprising a frequency modulated first motorspeed signal and a first motor enable signal; b) transmitting the firstroller motor control signals to the roller motor to cause the motor todrive the roller to move bags through the print station; c) receivingsecond roller motor control signals from a bagging machine controllercomprising a frequency modulated second motor speed signal and a secondmotor enable signal; d) transmitting the second roller motor controlsignals to the roller motor to cause the motor to drive the roller tomove bags to the final station; and e) repeating steps a-d such that atany given time either first roller motor speed signal or the secondroller motor speed signal, but not both simultaneously, are beingtransmitted to the roller motor by providing a control signal to amultiplexer that provides a selected speed signal to the roller motorbased on the control signal and wherein the speed signals are generatedby selecting resistor components that are coupled to a voltagecontrolled oscillator to provide a frequency modulated motor speedsignal.
 16. The method of claim 15 wherein the first motor speed signalcorresponds to a slower roller speed than the second motor speed signal.17. The method of claim 15 wherein at least one of the roller motorcontrol signals comprises a signal that corresponds to a rate ofacceleration for the motor.
 18. The method of claim 15 wherein step e isperformed by forming a logical OR combination of motor enable signalsfrom the printer controller and the bagging machine controller.
 19. Anapparatus for printing indicia on bags perforatedly interconnected in acontinuous web comprising: a) a bagging machine comprising an initialstation for mounting a stock quantity of empty bags, a plurality oftensioning rollers for moving the web of bags from the initial station,through a print station, to a final station; b) a motor connected to atleast one of the tensioning rollers for driving the roller to move theweb of bags; c) a printer controller for providing first motor controlsignals for controlling the motor; d) a bagging machine controller forproviding second motor control signals for controlling the motor; e) asequencer for receiving the first and second motor control signals andpassing one, but not both, of the signals to the motor according to acontrol algorithm.
 20. The apparatus of claim 19 wherein the sequencercomprises a multiplexer that provides either the first or second motorcontrol signal to the roller motor from either the printer controller orthe bagging machine controller according to the control algorithm. 21.The apparatus of claim 19 wherein the sequencer comprises means forforming a logical OR combination of the first and second motor controlsignals.
 22. The apparatus of claim 19 comprising means for selectingresistor components that are coupled to a voltage controlled oscillatorto provide a frequency modulated motor speed signal.
 23. The apparatusof claim 19 comprising a perforation detector for sensing perforationsbetween bags in the web and transmitting a perforation signal thatindicates a perforation is present to the bagging machine controller.24. The apparatus of claim 23 wherein the bagging machine controllerreceives the perforation signal and uses the signal to monitor theposition of the web of bags.
 25. The apparatus of claim 23 wherein theperforation detector comprises: a generally hemispherical sensing tip; abiasing spring engaging the sensing tip and urging it toward aconducting plate; a voltage source in electrical communication with thesensing tip for energizing the sensing tip to cause a potentialdifference between the sensing tip and the conducting plate; and whereinthe web of bags is fed between the sensing tip and the conducting plateand wherein perforations between the bags permit an arc to pass betweenthe sensing tip and conducting plate to register a perforation signatureand wherein in the absence of perforations, arcing is prevented.
 26. Anperforation sensing apparatus for sensing perforations between bags inan interconnected web and providing a signal indicative that aperforation is present comprising: a generally hemispherical sensingtip; a biasing spring engaging the sensing tip and urging it toward aconducting plate; a voltage source in electrical communication with thesensing tip for energizing the sensing tip to cause a potentialdifference between the sensing tip and the conducting plate; and whereinthe web of bags is fed between the sensing tip and the conducting plateand wherein perforations between the bags permit an arc to pass betweenthe sensing tip and conducting plate to register a perforation signatureand wherein in the absence of perforations, arcing is prevented.